Method of making fuel briquettes



Aug. 5, 1930. I c. v. MCINTIRE 1,772,033

METHOD OF MAKING FUEL BRIQUETTES Filed May 29 1926 A; ATTORNEYS CHARLES V. MCINTIRE,

Patented Aug. 5, 1930 OF FAIRMONT, WEST VIRGINIA, ASSIGNOR TO CONSOLIDATION coAL rnonuc'rs COMPANY, OF }ZV1LMINGTON, DELAWARE, A CORPORATION or DELAWARE METHOD or MAKING FUEL namun'r'rns Application filed May 29,

This invention relates to fuel briquettes of the type described in the Smith Patent No.

' 1,276,429, and has for its object to improve the method and product of that patent.

The briquette of the Smith patent has a hard, dense strong physical structure, a specific gravity of 1.3 or more, and a volatile content of less than 3%-a briquette in short resembling anthracite as closely as possible. The base of this briquette is a semi-anthracite having a naturally low volatile content, or, more commonly, a semi-coke made by partially carbonizing bituminous coal at low temerature to reduce its volatile to about 10%.

his base material is crushed, mixed with a quantity of coal tar pitch, or its equivalent, sufiicient to bring-the volatile content of the whole, exclusive of water, to form 11 to 17 andthe mixture briquetted. The volatile content of the briquette at this stage of the process is important and great stress is laid upon it in the patent. The raw briquette is then subjected to a second and final carbonizatlon at tem eratures ranging from 1400" F. to 2000 .in a. retort of the type illustrated in Smith Patent No. 1,409,597, until the volatile content has been reduced to below 3% and the hard, dense anthracitio structure described above has been produced.

In carrying out this process in actual practice, using retorts of the Smith Patent No. 1,409,597, 16 inches Wide I have found that the time required to reduce the volatile content of the briquettes to less than 3% at the temperatures specified makes the process impracticable, and that even when employing recarbonization temperatures as high as 2600 F., the average time required for carbonizing a charge of briquettes, is about 12 hours. Not only is the cost of o erating at such high temperatures prohi itive, but it is almost impossible to carbonize a briquette successfully by placing it against a hot surface 1600 F. or higher (as is necessary in the continuous commercial operation of the Smith process) the sudden and rapid evolution of gas usually causing it to s lit open. Thus, although hard, dense, low vo atile briquettes can be made by the Smith method and in the Smith appa- 1926. Serial No. 112,497.

ratus, the time and care required and the expense entailed are excessive. Besides, high temperature carbonization destroys desirable cell structure by too much shrinkage and too great reduction in volatile.

I have discovered that a highly satisfactory and, in many respects, superior fuel can be made by retaining much more than 3% of the volatile constituents in the briquette-- that instead of recarbonizing the raw briquette until the volatile content is reduced to content be reduced only to about 8% to 13%. The practical advantage of this is two-foldfirst, a better briquette is obtained, and, second the rocess of making it is improved by cutting own both the time and temperature of the carbonization, thus greatly reducing the cost of operation, and also greatly increasing'the certitude of producing a sound product. I have also discovered that an improved briquette is obtained if the volatile content of the raw fuel before recarbonization be about 18% to 20% instead of less than this amount.

As a further improvement I carbonize my briquettes without permitting them to come in contact with the hot. Walls of the retort ovens, supporting them in thin layers upon a screen supported between the fioor and the roof of the ovens, so that practically all of the heat is delivered in the form of radiant energy with little or no danger of local overheating.

The resulting fuel is not so dense and strong as the product of more intensive recarbonization, but its high volatile content together with its peculiar cellular structure, resembling charcoal, give it a combination of properties which are far more desirable than mere density; yet it has all the toughness and strength necessary for commercial handling. It can also be produced more efiiciently and at lower cost.

.In order that my invention may be more clearly understood I shall now give a specific example of the manner in which I prefer to carry it out, starting with the raw coal and ending up with the recarbonized briquettes: Bituminous coal having a volatile content of less than 3%, it is suflicient if that about 25% to 45% is fed to a primary retort of the type illustrated in my Patents Nos. 1,457,083 and 1,479,827 and heated at about 750 F. to 850 F. while being agitated. The coal melts .into a plastic mass shortly after it enters the retort and extends in this condition for about half the length of the'retort. From that point on, however, as more and I more of the volatile is removed the product becomes more and more granular in characterand when finally discharged is fully converted into a semi-coke containing about to volatile. As the coke leaves the retort it is quenched by means of steam. The larger lumps are screened out, allowed to stand for an hour while being sprayed occasionally Iand then the whole product ground to pass a 6 mesh screen. Other methods of forming the semi-coke might be employed; the foregoing is given as one which I have found to be satisfactory.

The ulverized semi-coke is then fluxed with ablnder of 10% to 12% of coal tar pitch or other equivalent hydrocarbon .to form a mash which is briquetted in a press of the standard Belgium type. The pitch is pref erably added in liquid form and is usually a by-product of the process itself. The raw briquettes, containing about 18% to 20% volatile matter exclusive of Water, are then ready for the recarbonization step.

In the accompanying drawing 1 have illus trated, more or less diagrammatically, a re-' tort in which I recarbonize the briquettes in accordance with my process. In these drawings Figure 1 is a verticaltransverse section through the retort showing a plurality of superimposed mufiie ovens with the briqliliettes supported upon screen trays between t e upper and lower walls of the ovens; Figure 2 is a longitudinal section taken along line 22 of Figure 1 and Figure 3 is a perspective view of two of thescrcen trays which support the briquettes within the ovens.

The retort illustrated comprises a series of superposed ovens l which are heated from above and below by means of transverse heat flues 2 to which gas and air are fed through conduits 3 and 4 respectively and from which the products of combustion are removed through waste heat lines 5. The bri uettes 6 are placed in a thin layer, prefera 1y two rows deep, upon a heating resistant screen cloth 7 of a tray 8 and placed within an oven. The tray is provided with longitudinal flanges 9 which are received and supported by longitudinal recesses 10 in the side walls of the oven. As clearly illustrated in Figures 1 and 2 the briquettes are supported sub-. stantially mid-way between the bottom and roof of the oven and are therefore heated by radiant heat, never coming into contact with the hot flue walls. a

The temperature of the roof and floor of the ovens is about 1200 to 1400 F. With a chamber about 12 high, two layers of briquettes containing an initial volatile content from 18% to 20% can be carbonized down to about 8% to 13% volatile in thirty minutes,

and as the two layers weigh from 1 0 to 12 pounds per square foot, this gives a carbonizing rate for the oven of from 10 to 12 pounds per square foot of heatedsurface per hour, each square foot of tray having two square feet of heated surface. After the briquettes have remained Within the oven for about thirty minutes the trays are withdrawn, the briquettes removed and quenched, and the trays re-loaded and returned to the oven.

The resultant briquettes with their vola; tile content from 8% to 13% compare favorably with anthracite i burning qualities, If carbonized to 10% or below the are abso' lutely smokeless, while those of hlgher volatile content will give off a light brown or yellow smoke for a few minutes after-being placed on the fire. They are not so strong and dense as the -lower volatile briquettes made by recarboii izing at higher temperatures and for lon er periods, but they have a peculiar cellular/structure resembling charcoal which imparts combustion properties far more valuable than'mere density While at the same time they have sulficient strength and density to enable them to Withstand commercial handling Without disintegration. Not only is the prpduct of my process highly desirable, but the," process itself with its low temperature recarbonization can be carried on much more economically than (the high temperature process and produce a much higher percentage of perfect briquettes.

I claim:

1. The method of making fuel briquettes to 20% volatile matter exclusive of water-f] I and one which forms a coherent coke oarbonization, briquetting the mixtur' carbonizing the briquettes, so,that he sultant carbonized briquettes conta 8% to 13% volatile matte r. "Q9

3. The method of making fuel? which comprises mixing a partial ized pulverized, s0lid, carbonaceous -uel'containing about 10% to 15%;iyolatile matter with about 10% to 12% of-a fhydrocarbon binder so as to form a mixture having a vola; 1' tile content of about 18% to 20% exclusive of water and one which formsa coherent coke upon carbonization, briquetting the mixture, and carbonizing the briquettes so as to reduce the volatile content to about 8% to 13%.

4. The method of making fuel briquettes which comprises making a mash of a pul verized semi-coke containing about 10% to 15% volatile matter, exclusive of Water and about 10% to 12% coal tar pitch, briquetting the mash, and carbonizing the briquettes, so that the resultant carbonized briquettes have a volatile content of about 8% to 13%.

5. The method of making fuel briquettes which comprises partially carbonizing a high volatile coal to form a semi-coke, pulverizing the semi-coke, mixing with it a hydrocarbon binder, the mixture containing from 18% to 20% volatile matter exclusive of water, briquetting the mixture, and carbonizing the briquettes until their volatile content lies between 8% and 13%.

6. The method of making fuel briquettes which comprises partially carbonizing a high volatile coal so as to form a soft porous semicoke having a volatile content of about 10% to 15%, pulverizing the semi-coke, mixing with it a binder of about 10% to 12% of coal tar pitch, briquetting the mixture, and carbonizing the briquettes so as to form a when ent coke containing from 8% to 13% volatile matter.

7. The method of making fuel briquettes which comprises mixing a pulverized, solid, carbonaceous fuel with a hydrocarbon binder so as to form a mixture containing about 18% to 20% volatile matter exclusive of water and one which forms a coherent coke upon carbonization, briquetting the mixture and carbonizing the briquettes at about 1200 F. to 14:00 F.

8. The method of making fuel briquettes which comprises mixing a pulverized, solid, carbonaceous fuel with a hydrocarbon binder so as to form a mixture containing about 18% to 20% volatile matter exclusive of water and one which forms a coherent coke upon carbonization, briquetting the mixture, and carbonizing the briquettes at about 1200 F. to p 1400 F. so that the resultant carbonizing briquettes contain about 8% to 13% volatile matter.

9. The method of making fuel briquettes which comprises making a mash of a pulverized semi-coke containing about 10% to 15% volatile matter, exclusive of water and about 10% to 12% coal tar pitch, briquetting the mash, and carbonizing the briquettes at about 1200 F. to 1400 F. so that the result-- ant carbonized briquettes have a volatile content of about 8% to 13%.

10. The method of making fuel briquettes which comprises making a mash of a pulverized semi-coke containing about 10% to 15% volatile matter, exclusive of water and about 10% to 12% coal tar pitch, briquctting the mash, and carbonizing the briquettes by subto 20% volatile matter exclusive of water and one which forms a coherent coke upon carbonization briquetting the mixtures and carbonizing the briquettes by subjecting a thin layer-of them to radiant heat for about 30 minutes, so that the resultant carbonized briquettes contain about 8% to 13% volatile matter.

12. The method of making fuel briquettes which comprises partially carbonizing a hi h volatile coal to form a soft porous semi-co e having a volatile content of about 10% to 15%, pulverizing the semi-coke, mixing with it a binder of about 10% to 12%- =,of coal tar pitch, briquetting the mixture, and carbonizing the briquettes so as to form a coherent coke by subjecting a thin layer of them to radiant heat for about 30 minutes at 1200 F. to 1400 F. so that the g resultant carbonized briquettes contain from 8% to 13% volatile matter.

In testimony whereof I afix my signature.

CHARLES V. MGINTIRE. 

